Thermal paper is used in fax machines as a communication medium for text and graphics, serving as fax paper; in medical and measurement systems as recording material, such as electrocardiogram sheets and thermal instrument recording paper; as printing paper in internet terminals; and in commercial activities, for making trademarks, POS (Point of Sale) certificates, etc., with fax paper accounting for the largest share of usage.
The manufacturing principle of thermal paper involves coating a plain paper base with microparticles of powder, composed of colorless dyes such as phenols or other acidic substances, separated by a thin film. Under heating conditions, the film melts, and the powder mixes, triggering a color reaction. The text on thermal paper is unstable and easily fades, making documents difficult to read. Lottery tickets commonly use thermal paper.
Ordinary thermal paper is not suitable for long-term storage, but good quality thermal paper can be preserved for 30 years or even longer.